Effects of Bumper Integration on Low-, Mid-, and High-Resolution Imaging Radars

Radar sensors are widely used for advanced driver assistance systems as they enable an accurate perception of the surroundings. Typically, the sensors are hidden behind bumpers or radomes to protect them from environmental influences, but also for design reasons. Since the bumper possibly affects not only the receive power but also the direction-of-arrival (DoA) estimation, the bumper is typically taken into account in the calibration. Thus, a re-calibration is required after a bumper change or a paint job. In this work, the influence of the bumper on the DoA estimation performance and radar image quality is compared for low-, mid-, and high-resolution sensors. Therefore, a thorough measurement series is conducted. As reference, a setup without bumper is deployed and no re-calibrations are conducted, i.e. the radar is calibrated only once without the bumper. The degradation due to a muddy bumper that can not be included in the calibration is analyzed, also. In all cases, the high-resolution radar shows the greatest robustness, with a DoA estimation error of only $0.2^\circ$ for the muddy bumper, compared to $0.8^\circ$ and $22^\circ$ for the mid- and low-resolution sensor.